Louver and butterfly isolation valves for clean industrial duct systems, and gas turbines in particular, impose an unwanted pressure drop in the duct flow passing throught the open valve. The pressure drop, due to obstructions in the flow, decreases overall system performance. Moreover, in order to provide low leakage rates, louver and butterfly dampers require the addition of internal seal components which can become detached during normal operation.
Although industrial guillotine type dampers do not obstruct gas flow, their installation into a large duct system typically requires the addition of a supplemental support to carry the increased loading due to the weight of current guillotine designs. Guillotine dampers can achieve low leakage rates, but at the expense of an external seal air fan system. Specifically in the case of gas turbine inlet duct systems, obstructions in the flow path lead to a loss in operating efficiency and shortened turbine life. The possiblity of the gas turbine ingesting dislodged components also limits the use of unnecessary internal components. New gas turbine designs such as the MS 7000FA manufactured by General Electric contain internal components produced with high alloy materials that, during periods of turbine inactivity, are sensitive to moisture corrosion. Moisture will naturally condense out of the ambient air under the proper atmospheric conditions, causing corrosion of the turbine internals leading to a loss of turbine performance and shortened life.
It is therefore an object of the present invention to provide a roll-up damper that operates as a tight shutoff valve, opening and closing a flow path in a large ducting system while minimizing unwanted pressure drop and excessive damper weight.